Combined cycle electrical generating systems using solar and gas turbine units are probably known as illustrated in U.S. Pat. No. 5,444,972. In addition it is believed that Bechtel Corporation of San Francisco, Calif. have designs that have added to a standard General Electric gas turbine power plant (which by the way also used high pressure and low pressure steam turbines), a solar evaporator. However, in both of the above installations, there was no specific effort to optimize the overall system. Rather the solar energy portion of the system was merely added to the combined cycle, utilizing the original gas turbine steam generation equipment and cycle layout as originally designed for fuel firing.